Note: Descriptions are shown in the official language in which they were submitted.
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A Polyisocyanurate Foam for Sandwich Panel with Low Processing Temperature and
Enhanced
Adhesion
Technical field of the invention
The present invention is directed to a polyisocyanurate foam, its use in a
sandwich panel, a
sandwich panel comprising the the foam and a process for preparing the
sandwich panel.
Background of the invenfion
Sandwich panels having cellular cores are notable for their light weight and
high strength. Con-
ventionally, such panels are constructed by sandwiching a cellular core having
low strength be-
tween two facings, each of which is much thinner than the cellular core but
has excellent me-
chanical properties.
Due to the higher and higher flame resistance (FR) requirement in the sandwich
panel market,
polyisocyanurate (PI R) foam becomes more and more popular for its good FR
property.
However, there are two main problems for PI R sandwich panel production: a)
bad adhesion
between the PI R foam and the metal facing, b) high processing requirement,
e.g. >60 C. Many
customers use an adhesion promoter to solve the adhesion problem. Moreover,
the cost of the
high processing temperature is high, especially in winter. Both of the
problems add the cost of
the sandwich panel production.
Polyurethane/polyisocyanurate foams having improved adhesion properties have
been
disclosed in many publications.
For example, ON 102666630 A discloses a polyurethane/polyisocyanurate foam
that can be
obtained by reacting A) a polyol component comprising Al) an aromatic
polyester polyol, A2) a
polyether polyol started on a carbohydrate polyol, and A3) a polyether polyol
started on an eth-
ylene glycol, wherein the total hydroxyl number of the polyol component A) is
from 150 mg
KOH/g to 300 mg KOH/g; with B) a polyisocyanate component, wherein the
equivalent ratio of
.. NCO groups to the sum of the hydrogen atoms that are reactive with respect
to NCO groups is
from 110:100 to 200:100. It was said that the foam has improved bonding
properties with
the facing and is suitable for producing composite elements without requiring
the use of an addi-
tional bonding agent. However, the NCO index was reduced to 110 - 200, and
this causes the
foam to become a polyurethane/polyisocyanurate blend (PUIR) foam. The
polyurethane part will
improve the adhesion property. However, the flame resistance property of the
PUIR foam is
worse than the PI R foam.
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Summary of the invention
An object of the present invention is to provide a polyisocyanurate foam
showing a good
adhesion property even without adhesion promoter, an improved processability
at a lower
temperature (60 C) and an improved flame resistance property.
The object can be achieved by a polyisocyanurate foam obtainable by reacting
A) a polyol
component comprising: Al) a polyester ployol, A2) a short-chain polyether
polyol, and A3) a
long-chain polyether polyol; with B) a polyisocyanate component with an NCO
index from about
210 to about 500.
In a first aspect of the invention, there is provided a polyisocyanurate foam
obtainable by
reacting A) a polyol component comprising: Al) a polyester ployol, A2) a short-
chain polyether
polyol, and A3) a long-chain polyether polyol; with B) a polyisocyanate
component with an NCO
index from about 210 to about 500.
In a second aspect of the invention, there is provided the use of the
polyisocyanurate foam of
the present invention in sandwich panel.
In a third aspect of the invention, there is provided a sandwich panel
comprising the
polyisocyanurate foam of the present invention.
In a fourth aspect of the present invention, there is provided a process for
preparing the
sandwich panel of the present invention, comprising the step of applying a
reaction mixture that
yields the polyisocyanurate foam of the present inveniton to a facing.
Detailed description of the invention
In one aspect, the present invention is directed to a polyisocyanurate foam
obtainable by
reacting A) a polyol component comprising: Al) a polyester ployol, A2) a short-
chain polyether
polyol, and A3) a long-chain polyether polyol; with B) a polyisocyanate
component with an NCO
index from about 210 to about 500.
Polyester ployol Al) can be for example, an aromatic polyester ployol. The
aromatic polyester
ployol can be, for example, a polycondensation product of di- as well as
optionally tri- or more
functional alcohols and aromatic di- as well as optionally tri- and more
functional carboxylic
acids or hydroxycarboxylic acids or lactones. Instead of the free
polycarboxylic acids, the
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corresponding polycarboxylic acid anhydrides or corresponding polycarboxylic
acid esters of
lower alcohols can also be used to prepare the polyesters.
Examples of suitable diols for the preparation of the polyester ployol are
ethylene glycol,
butylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-
propanediol, 1,3-
butanediol, 1,4-butanediol and the isomers thereof, 1,6-hexanediol and the
isomers thereof, or
neopentyl glycol, also polyalkylene glycols such as polyethylene glycol, with
ethylene glycol,
butylene glycol, 1,6-hexanediol and the isomers thereof, and neopentyl glycol
being preferred.
In addition, polyols such as trimethylolpropane, glycerol, erythritol,
pentaerythritol, or
trimethylolbenzene can also be used.
As aromatic dicarboxylic acids, for example, phthalic acid, isophthalic acid,
terephthalic acid,
naphthalenedicarboxylic acids and/or tetrachlorophthalic acid may be used. The
corresponding
anhydrides can also be used as the acid source.
The polyester polyol Al) preferably has a hydroxyl number from about 50 to
about 750 mg
KOH/g, more preferably from about 100 to about 500 mg KOH/g, even more
preferably from
about 150 to about 400 mg KOH/g, most preferably from about 150 to about 300
mg KOH/g.
The number-averaged molecular weight of the polyester polyol Al) may be from
about 100 to
about 3000, preferably from about 200 to about 2000, more from about 300 to
about 1000, most
from about 400 to about 800, as measured by gel permeation chromatography
(GPO) using
polystyrene standard.
The amount of the polyester ployol Al) can be from about 1 to about 35%,
preferably from
about 5 to about 30%, more preferably from about 15 to about 25%, based on the
total weight of
the components A) and B).
The polyether polyols in the short-chain polyether polyol A2) and the long-
chain polyether polyol
A3) are obtained by known processes, for example via anionic or cationic
polymerization of
alkylene oxides with addition of at least one starter molecule comprising from
2 to 8, preferably
from 2 to 6, and particularly preferably from 2 to 4, reactive hydrogen atoms,
in the presence of
catalysts. Catalysts used can comprise alkali metal hydroxides, such as sodium
hydroxide or
potassium hydroxide, or alkali metal alcoholates, such as sodium methoxide,
sodium ethoxide,
potassium ethoxide, or potassium isopropoxide, or, in the case of cationic
polymerization, Lewis
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acids, such as antimony pentachloride, boron trifluoride etherate, or
bleaching earth. Other
catalysts that can be used are double-metal cyanide compounds, known as DMC
catalysts.
The alkylene oxides used for preparing A2) and A3) comprise one or more
compounds having
from 2 to 8 carbon atoms in the alkylene moiety, e.g. tetrahydrofuran,
ethylene oxide, propylene
oxide, 1,2-butylene oxide, 2,3-butylene oxide or styrene oxide, in each case
alone or in the form
of a mixture, and preferably propylene oxide and/or ethylene oxide.
Examples of starter molecules that can be used are ethylene glycol, diethylene
glycol, glycerol,
trimethylolpropane, pentaerythritol, sugar derivatives, such as sucrose,
hexitol derivatives, such
as sorbitol, methylamine, ethylamine, isopropylamine, butylamine, benzylamine,
aniline,
toluidine, toluenediamine, naphthylamine, ethylenediamine, diethylenetriamine,
4,4'-
methylenedianiline, 1,3-propanediamine, 1,6-hexanediamine, ethanolamine,
diethanolamine,
triethanolamine, and also other di- or polyhydric alcohols, or di- or
polybasic amines.
In a preferred embodiment, the short-chain polyether polyol A2) consists of
the reaction product
of ethylene oxide and/or propylene oxide, particularly propylene oxide,
initiated on dimethylol
propane, trimethylol propane or glycerine or ethanediol, preferably on
ethanediol.
The short-chain polyether polyol A2) has an OH number from about 100 to about
1250 mg
KOH/g, more preferably from about 100 to about 950 mg KOH/g, particularly
preferred from
about 100 to about 500 mg KOH/g, most preferably from about 100 to about 300
mg KOH/g.
The number-averaged molecular weight of the short-chain polyether polyol A2)
may be from
about 100 to about 1000, preferably from about 200 to about 900, more from
about 300 to about
800, most from about 400 to about 600.
The amount of the the short-chain polyether polyol A2) can be from about 1 to
about 20% by
weight, preferably from about 1 to about 10%, more preferably from about 1 to
about 6%, based
on the total weight of the components A) and B).
In a perferable embodiment, the long-chain polyether polyol A3) consists of
the reaction product
of ethylene oxide and/or propylene oxide, particularly ethylene oxide and
propylene oxide,
initiated on dimethylol propane, trimethylol propane or glycerine, preferably
on glycerine.
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The long-chain polyether polyol A3) has an OH number from about 10 to about
1000mg KOH/g,
more preferably from about 20 to about 500 mg KOH/g, particularly preferred
from about 30 to
about 200 mg KOH/g, most preferably from about 40 to about 100 mg KOH/g.
5 The number-averaged molecular weight of the long-chain polyether polyol
A3) may be from
more than about 1000 to about 5000, preferably from about 2000 to about 5000,
more
preferably from about 3000 to about 5000, most preferably from about 3000 to
about 4000.
It has surprisingly found that when using the long-chain polyether polyol A3)
as the starting
material, the adhesion strength of the resultant PIR foam would be greatly
improved.
The amount of the long-chain polyether polyol A3) can be from about 1 to about
20%, preferably
from about 1 to about 10%, more preferably from about 1 to about 5%, based on
the total
weight of the components A) and B).
The polyisocyanate component B) can be monomeric polyisocyanate or
polyisocyanate
prepolymer. The monomeric polyisocyanate can be, for example, aliphatic,
cycloaliphatic, or
aromatic isocyanates. Examples are diphenylmethane 2,2'-, 2,4-, and 4,4'-
diisocyanate, the
mixtures of monomeric diphenylmethane diisocyanates and of diphenylmethane
diisocyanate
homologs having a greater number of rings (polymeric MDI), isophorone
diisocyanate (IPDI) or
its oligomers, tolylene diisocyanate (TDI), for example tolylene diisoyanate
isomers such as
tolylene 2,4- or 2,6-diisocyanate, or a mixture of these, tetramethylene
diisocyanate or its
oligomers, hexamethylene diisocyanate (H Dl) or its oligomers, naphthylene
diisocyanate (N Dl),
or a mixture thereof. The preferable monomeric polyisocyanate are MDI.
The polyisocyanate prepolymers are obtainable by reacting an excess of the
polyisocyanates
with compounds having at least two groups reactive toward isocyanates, to give
the prepolymer.
The polyisocyanates used to prepare the prepolymer can be, for example, those
above-
mentioned for the monomeric polyisocyanate.
The NCO index of the polyisocyanate prepolymers of the invention is preferably
from about 210
to about 500, more preferably from about 250 to about 500, most preferably
from about 300 to
about 500. The higher NCO index is the key technical pathway to improve FR
performance in
panel application, which will meet the FR requirment in panel apllication.
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The reaction for preparign the PI R foam is advantageously carried out in the
presence of a
catalyst. The catalyst that can be used in the present invention may be, for
example, basic
amines, e.g. secondary aliphatic amines, imidazoles, amidines, and also
alkanolamines, Lewis
acids, or organometallic compounds, in particular those based on tin.
Polyamines such as
N,N,N',N",N"-pentamethyldiethylenetriamine could also be used, optionally
together with
potassium acetate.
Catalyst systems composed of a mixture of various catalysts can also be used.
In a preferable
embodiment, the catalyst may additionally comprise the so-called delay
catalyst. Among them,
.. DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) based amine salt catalyst are
preferable, more
preferably tertiary amine.
It was surprisingly found that when using the delay catalyst, especially the
DBU based amine
salt as the catalyst, the adhesion strength of the resultant PI R foam would
be greatly improved.
The amount of the catalyst can be from about 0.1 to about 5%, preferably from
about 0.1 to
about 4.5%, more preferably from about 0.1 to about 3.0%, even more preferably
from about
0.15 to about 2.5%, most preferably from about 0.2 to about 1.0%, in each case
based on the
total weight of the components A) and B).
In the process of the present invention for prepare the PI R foam, various
auxiliaries and/or
additives, for example, flame retardants, plasticizers, surfactants, blowing
agents, stabilizers,
cell regulators, fillers, pigments, dyes, antioxidants, hydrolysis
stabilizers, antistatic agents,
fungistatic agents, and bacteriostatic agents etc. can be used.
The flame retardants that can be used can be phosphorus-containing flame
retardant, such as
i) phosphorus-containing flame retardants having a low-molecular-weight. These
compounds
preferably have a molar mass below 300 g/mol, specifically below 300 g/mol,
preferably below
200 g/mol, and particularly preferably from 150 to 190 g/mol, and preferably
have fewer than 4
.. phosphorus atoms in the molecule, especially fewer than 3, more especially
fewer than 2, and
especially 1 phosphorus atom. Preference is given to phosphonates and/or
phosphates. The
phosphonates and/or phosphates may further comprise halogen atoms in the
molecules.
Particular preference is given to phosphates and phosphonates selected from
diethyl
ethanephosphonate (DEEP), dimethyl propylphosphonate (DMPP), and triethyl
phosphate
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(TEP), and further preference is given to those selected from diethyl
ethanephosphonate
(DEEP) and triethyl phosphate (TEP),
ii) Another group of phosphorus containing compounds which do not react with
isocyanates has
a higher-molecular-weight, preferably with a molar mass above 300 g/mol.
Preferably they have
at least 1 phosphorus atom in the molecule. Preference is given to
phosphonates and/or
phosphates, especially phosphates. Preferred examples for these are diphenyl
cresyl
phosphate (DPC), tris(2-chlorisopropyl)phosphate (TCPP) and/or triphenyl
phosphate, in
particular diphenyl cresyl phosphate,
iii) Ammonium phosphate or ammonium polyphosphate.
In a preferred embodiment of the invention, the flame retardant is selected
from diethyl
ethylphosphonate (DEEP), dimethyl propylphosphonate (DMPP), triethyl phosphate
(TEP) and
tris(2-chlorisopropyl) phosphate (TCPP).
The flame retardants can be used alone or in a form of a mixture.
The amount of the flame retardant can be from 0 to about 10%, preferably from
about 0.1 to
about 8.0%, more preferably from about 0.5 to about 7.0%, even more preferably
from about
0.8 to about 6.5%, most preferably from about 0.8 to about 6.0% by weight, in
each case based
on the total weight of the components A) and B)
It has surprisingly found that when using the combination of TEP with TCPP,
the adhesion
strength of the resultant PI R foam would be greatly improved. In a preferable
embodiment of the
present invention, the weight ratio of TEP to TCPP may be from about 0.1 to
about 10.0,
preferably from about 0.2 to about 5.0, more preferably from about 0.5 to
about 2Ø
The blowing agents that can be used are chemical blowing agents, such as water
and/or formic
acid, these reacting with isocyanate groups with elimination of carbon dioxide
and, respectively,
carbon dioxide and carbon monoxide. The compounds known as physical blowing
agents can
also be used in combination with water or preferably instead of water. These
are compounds
being inert with respect to the starting components, mostly liquid at room
temperature, and
evaporating under the conditions of the urethane reaction. The boiling point
of these
compounds is preferably below 60 C. Among the physical blowing agents there
are also
compounds which are gaseous at room temperature and which are introduced or
dissolved into
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the starting components under pressure, examples being carbon dioxide, low-
boiling alkanes,
and fluoroalkanes.
The blowing agents are mostly selected from alkanes, formic acid and and/or
cycloalkanes
having at least 4 carbon atoms, dialkyl ethers, esters, ketones, acetals,
fluoroalkanes having
from 1 to 8 carbon atoms, and tetraalkylsilanes having from 1 to 3 carbon
atoms in the alkyl
chain, in particular tetramethylsilane.
Examples which may be mentioned are propane, n-butane, isobutane, cyclobutane,
n-pentane,
isopentane, cyclopentane, cyclohexane, dimethyl ether, methyl ethyl ether,
methyl butyl ether,
methyl formate, acetone, and also fluoroalkanes which can be degraded in the
troposphere and
therefore do not damage the ozone layer, e.g. trifluoromethane,
difluoromethane, 1,1,1,3,3-
pentafluorobutane, 1,1,1,3,3-pentafluoropropane, 1,1,1,2-tetrafluoroethane,
difluoroethane, and
heptafluoropropane. The physical blowing agents mentioned may be used alone or
in any
desired combinations with one another.
The amount of water is preferred in a range of 0.1 to 2.0 % by weight, based
on the weight of
the components A) and B).
Further details concerning the starting materials used for carrying out the
inventive process,
such as plasticizers, surfactants, blowing agents, stabilizers, cell
regulators, fillers, pigments,
dyes, antioxidants, hydrolysis stabilizers, antistatic agents, fungistatic
agents, and bacteriostatic
agents etc. may be found by way of example in Kunststoffhandbuch [Plastics
Handbook],
volume 7, "Polyurethane", Carl-Hanser-Verlag Munich, 3rd edition, 1993.
The PI R foam obtained according to the present invention shows an improved
adhesion
strength and an improved processability at lower temperature (60 C) in
comparison to the
already commercialized PI R system; simultaneously it shows an excellent flame
resistance.
In a preferable embodiment, the polyisocynaurate foam is obtainable by
reacting A) a polyol
component comprising: Al) a polyester ployol, A2) a short-chain polyether
polyol, A3) of a long-
chain polyols, ; with B) a polyisocyanate component having an NCO Index from
about 210 to
about 500 in the presence of Cl) flame retardants TEP and TCPP and 02)
catalyst package
which is in a form of delay catalyst package.
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It has been proved that the components A3, Cl and 02 in the reaction mixture
of the present
invention could bring about the effect of improving the adhesion, lowing the
processing
temperature and improving the flame resistance. The present invention combines
the 3 factors
together to implement the advantageous effect. Therefore, in a preferable
embodiment, the
process for preparing the polyisocyanurate foam could be carried at a low
temperature, such as
60 C.
In one preferable embodiment, the polyisocynaurate foam is obtainable by
reacting A) a polyol
component comprising: Al) a polyester ployol in amount from about 15 to about
25%, A2) a
short-chain polyether polyol in amount from about 1 to about 20% by weight,
A3) a long-chain
polyols in amount from about 1 to about 5%; with B) a polyisocyanate component
having an
NCO Index of about 450 in the presence of Cl) flame retardants TEP and TCPP in
amount from
about 0.8 to about 6.0% and 02) catalyst package which is in a form of delay
catalyst package
in amount from about 0.2 to about 1.0%, in each case based on the total weight
of the
components A) and B).
In one embodiment, the reaction may be carried out at a temperature from about
20 C to about
60 C, more preferably from about 30 C to about 60 C, most preferably from
about 40 C to
about 60 C.
In another aspect, the present invention relates to a process for preparing a
sandwich panel,
wherein a reaction mixture that yields the PI R foam according to the
invention is applied to a
facing. The process can be carried out continuously or discontinuously. The
devices for contin-
uous production are known, for example, from DE 1 609 668 or DE 1 247 612.
In one embodiment of the process for preparing the sandwich panel, no adhesion
promoter lay-
er is arranged between the reaction mixture and the facing. In this case, the
improved adhesion
property of the present PI R foam guarantees the sufficient adhesion between
the foam and the
facing.
The facing could be made from paper, fiber or metal, preferably metal.
Suitable metals are, for
example, steel or aluminum.
The process for preparing the sandwich panel may be in the form of a twin-belt
conveyor pro-
cess. Pretreatment of the facings can be omitted owing to the adhesive
properties of the foam
according to the invention. This simplifies the process.
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In a further embodiment of the process according to the invention, the facing
has a temperature
of 60 C on application of the reaction mixture. This temperature can be
achieved in the pro-
duction plant, for example, by means of a preceding oven installation. For
twin-belt conveyor
5 systems in particular, the temperature is comparatively low, which again
brings about ad-
vantages in terms of process management and economy.
In an alternative embodiment, the sandwich panel can be prepared by means of a
molding
process. In this case, the premixed reaction mixture that yields the PI R foam
according to the
10 invention is applied to a facing which is previously arranged in a mold,
then reacted to form the
panel. The facing may be preheated, such as to a temperature 60 C. During the
reaction, the
temperature in the mold may be kept constantly by heating the mold. After a
certain time, such
as a period from 10 minutes to 2 hours, the finished panel is removed from the
mold.
The present invention also relates to the use of the foam according to the
present invention in a
sandwich panel, and a sandwich panel comprising the the foam according to the
present inven-
tion.
The sandwich panels of the present invention are available for a variety of
applications in
construction, such as industrial buildings, public buildings offices and
administration buildings,
cold storages, clean rooms, agricultural buildings, power plants, residential
houses and used in
transportation such as reefer container, trailer etc.
Description of Figures
Figures 1 and 2 illustrate the adhesion energies of the sandwich panels in the
examples.
Examples
The present invention will be explained in detail by means of the following
examples.
Unless otherwise stated, all the amounts of the components in the examples
refer to parts by
weight.
Premixed PI R foam-forming reactants indicated in Table 1 below were applied
to and foamed in
a box mold having a size of 40cmx40cmx9cm with a lower metal sheet which was
preheated to
60 C. During the reaction, the temperature in the mold was kept constantly at
60 C. After
keeping in the mold for 30 min, the finished sandwich panel was removed from
the mold.
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Table 1 Recipes of the PI R foams
A Component Control 1 Ex.1 Ex.2
Ex.3
Polyester polyol Al (polyethylene phthalate,
64.35 64.35 64.35 64.35
OFIv 170, Mn 594)
Short-chain Polyether Polyol A2
(polycondensate of PO initiated on Ethane- 16.04 11.04 16.04
16.04
1,2-diol, OFIv 190, Mn 590)
Long-chain polyether polyol
A3(polycondensate of P0/E0 initiated on - 5.00 - -
glycine, OFIv 56, Mn 3000)
TCPP (FR agent) 16.04 16.04 8.02
16.04
TEP (FR agent) - - 8.02
Silicone surfactant (TEGOSTAB available
1.61 1.61 1.61 1.61
from Evonik)
Catalyst package (Potassium acetate catalyst
and N,N,N',N",N"-Pentamethyl 1.55 1.54 1.55
1.6
diethylenetriamine catalyst in a ratio of 7:1)
Delay catalyst AS (DBU based tertiary amine
- - - 1
salt catalyst, CAS No.: 33918-18-2)
Water 1.00 1.00 1 1
Pentane (blowing agent) 15.00 17.00 15 17
B Component
M50S, available from BASF 198 198 198
198
NCO index 464.3 464.0 464
464
The adhesion energies of the resultant sandwich panels were measured according
the peel-off
test. The peel-off test could be carried out by using a Zwick machine
(available from BASF
company) to peel a 10 cm x20 cm metal sheet on the bottom side (For sandwich
panel the
adhesion of bottom side is worse than top side) off the foam surface from one
side. The force
and the distance were calculated to obtain the adhesion energy. The results
are shown in Fig-
ure 1 and Table 2.
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Table 2 Adhesion Energy of the resultant sandwich panels
Control 1 Ex.1 Ex.2 Ex.3
Adhesion Energy (10-3J) 1926.6 2536.6 2715.4 2480
Improvement - 31.6% 40.9% 28.7%
Comparing with the control 1, when using the long-chain polyol (EX.1), TCPP
and TEP
combination (EX.2), Delay catalyst (EX.3), the adhesion energies improve
31.6%, 40.9% and
28.7%, respectively.
In Ex. 4, the procedures for Ex. 1 to 3 were repeated by using the recipes in
Table 3 under 60
C, 50 C and 40 C, respectively, while control 2 is carried out under 60 C.
Table 3 Recipes of the PI R foams
A Component Control 2 Ex.4
Polyester polyol Al (polyethylene phthalate, 0Hv 170, 64.35 64.3
Mn 594) 5
Short-chain Polyether Polyol A2 (polycondensate of 16.04 11.0
PO initiated on Ethane-1,2-diol, 0Hv 190, Mn 590) 4
Long-chain polyether polyol A3(polycondensate of - 5.00
P0/E0 initiated on glycine, 0Hv 56, Mn 3000)
TCPP (FR agent) 16.04 8.02
TEP (FR agent) - 8.02
Silicone surfactant (TEGOSTAB available from 1.61 1.61
Evonik)
Catalyst package (Potassium acetate catalyst and 1.55 1.5
N,N,N',N",N"-Pentamethyldiethylenetriamine catalyst
in a ratio of 7:1)
Delay catalyst AS (DBU based tertiary amine salt - 1
catalyst, CAS No.: 33918-18-2)
Water 1.00 1.00
Pentane (blowing agent) 15.00 15.0
0
B Component
M50S, available from BASF 198 190
NCO index 464.3 464.
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0
The adhesion energies of the resultant sandwich panels were measured, and the
results are
shown in Figure 2 and Table 4, wherein EX-60 means under 60 C, EX4-50 under
50 C, EX4-
40 under 40 C.
Table 4 Adhesion Energy of the resultant sandwich panels
Control 2 Ex.4-60 Ex.4-50 Ex.4-40
Adhesion Energy(10-3J) 1983 2634 3421 3245
Improvement - 32.8%
72.5% 63.6%
Usually the lower temperature is bad for the PIR foam curing, because it will
cause worse
adhesion. Surprisingly, the examples show up to 70% increase in adhesion at
significantly lower
temperatures (50 C). Moreover, the flame resistances of the present examples
are similar with
the control.
